Main switch: 1 or 1+2?

[Peter Busschbach]

Greetings,I recently posted a question on DC power problems. Thanks for the responses. We have narrowed the problem down to a loose ground wire, although I haven't completely ruled out the gremlin issue yet During our investigation, my friend and I started debating a related issue with respect to the main switch.It was my understanding that you put the main switch on "1+2" while the engine was running in order to charge both batteries.My friend is of the opinion that the engine will always charge both batteries, no matter what the position of the main switch is, and that the main switch only serves to determine which battery is used to provide power. He therefore believes that the main switch should always be in the "1" or "2" position.Who is right?Peter

 

[BobM]

I think it depends...

...on how your boat is wired. Typically, the way a battery switch is designed, off is off. While the motor is running you can switch seamlessly between 1, 2 and 1& 2, but not to off or you could damage your alternator.However, the off is off statment presumes that the switch is wired that way and that there is not an isolator or integrator in use and no direct lines exist to the batteries from the alternator.See an interesting article below regarding isolators and integrators.Bob